The Large Animal Core will provide the facilities, management and technical expertise needed to supply MGH miniature swine and baboons and tissue samples for all projects of the proposed program as well as expert veterinary care, immunological reagents, and microbiologic diagnostic assays and support. Clinical samples will be distributed to maximize utilization of each animal for studies of clinically relevant regimens for xenotransplantation. The success of each component of this program is dependent on the quality, predictability, and accessibility of the animals, microbiologic support, and antibodies provided by this Core. Animal care is reviewed weekly at meetings of the principal investigators and the veterinary staff. The Aims of the Large Animal Core include: Aim 1: Production, quality control, tracking, and maintenance of MGH MHC inbred miniature swine including the novel MGH GalT-KO swine, with homozygous disruption of the a-1,3-galactosyltransferase gene (see Figures 1 and 2) and the GalT-KO-CD39 transgenic swine. Miniature swine production is monitored using a computerized, web-based system developed to coordinate the breeding, quality control, allocation, transportation and utilization of animals for each Project. Significant improvements in swine production have achieved an increased supply of swine adequate to the proposed studies. Aim 2: Purchase and maintenance of non-human primates Aim 3: Infectious Disease/Microbiology support for immunocompromised animals to provide molecular diagnostic assays for viral pathogens and advice on infectious disease management. Aim 4: Production, characterization, and maintenance of a unique series of monoclonal antibodies (MAb)reactive with swine and baboon cell surtace antigens to assess pig and baboon cell lineages and improve cellular depletion. Coordination of these activities is performed by Scott Arn, who directs all aspects of the development of the knockout swine, the provision of primates and maintenance of the detailed database used by all investigators of the Transplantation Biology Research Center at MGH. Dr. Jay Fishman will oversee infectious disease management and microbiologic diagnostics in xenotransplantation studies. Animal procedures are conducted by experienced transplant surgeons, veterinary clinicians and anesthesiologists in dedicated sterile operating rooms to optimize care and comfort.